Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634, USA.
J Exp Biol. 2012 Nov 15;215(Pt 22):3925-36. doi: 10.1242/jeb.072967.
Many species of gobiid fishes adhere to surfaces using a sucker formed from fusion of the pelvic fins. Juveniles of many amphidromous species use this pelvic sucker to scale waterfalls during migrations to upstream habitats after an oceanic larval phase. However, adults may still use suckers to re-scale waterfalls if displaced. If attachment force is proportional to sucker area and if growth of the sucker is isometric, then increases in the forces that climbing fish must resist might outpace adhesive capacity, causing climbing performance to decline through ontogeny. To test for such trends, we measured pressure differentials and adhesive suction forces generated by the pelvic sucker across wide size ranges in six goby species, including climbing and non-climbing taxa. Suction was achieved via two distinct growth strategies: (1) small suckers with isometric (or negatively allometric) scaling among climbing gobies and (2) large suckers with positively allometric growth in non-climbing gobies. Species using the first strategy show a high baseline of adhesive capacity that may aid climbing performance throughout ontogeny, with pressure differentials and suction forces much greater than expected if adhesion were a passive function of sucker area. In contrast, large suckers possessed by non-climbing species may help compensate for reduced pressure differentials, thereby producing suction sufficient to support body weight. Climbing Sicyopterus species also use oral suckers during climbing waterfalls, and these exhibited scaling patterns similar to those for pelvic suckers. However, oral suction force was considerably lower than that for pelvic suckers, reducing the ability for these fish to attach to substrates by the oral sucker alone.
许多虾虎鱼物种使用由腹鳍融合形成的吸盘附着在表面上。许多洄游性物种的幼鱼在海洋幼体阶段后，通过迁徙到上游栖息地时，利用这种腹鳍吸盘来攀爬瀑布。然而，如果成年鱼被转移，它们仍然可能使用吸盘重新攀爬瀑布。如果附着力与吸盘面积成正比，并且吸盘的生长是等尺生长，那么攀爬鱼类必须抵抗的力的增加可能超过其粘附能力，从而导致攀爬性能在个体发育过程中下降。为了测试这种趋势，我们测量了六种虾虎鱼物种的腹鳍吸盘在广泛的体型范围内产生的压差和粘附吸力，包括攀爬和非攀爬类群。吸力是通过两种不同的生长策略实现的：（1）在攀爬虾虎鱼中，吸盘体积等尺生长（或负异速生长）；（2）在非攀爬虾虎鱼中，吸盘体积正异速生长。使用第一种策略的物种具有较高的粘附能力基础，这可能有助于整个个体发育过程中的攀爬性能，其压差和吸力比如果粘附仅是吸盘面积的被动功能所预期的要大得多。相比之下，非攀爬物种拥有的大型吸盘可能有助于弥补压差的降低，从而产生足以支撑体重的吸力。攀爬的虾虎鱼属物种在攀爬瀑布时也使用口腔吸盘，这些吸盘的缩放模式与腹鳍吸盘相似。然而，口腔吸力远低于腹鳍吸盘的吸力，这降低了这些鱼仅通过口腔吸盘附着在基质上的能力。
